REGION — The first storm of the season was expected to bring widespread showers and isolated thunderstorms to San Diego County today, with heavy snow in the mountains.
The second of two fast-moving storms will arrive Sunday, with both storms keeping temperatures well below average and bringing strong, gusty winds to the mountains and deserts, according to the National Weather Service.
High temperatures in coastal areas Saturday were expected to be 60-65 degrees with overnight lows of 48-54. Highs in the western valleys will be 59- 64 with overnight lows of 42-50 and heavy rainfall in the afternoon. Highs near the foothills will be 52-57.
Highs in the mountains were expected to be 45-51 with overnight lows of 32-41. The NWS issued a wind advisory until 10 p.m. Sunday, with 40 mph winds possible Saturday afternoon. Desert highs will be 66-71 with overnight lows 44-55.
Fair, dry, and cool weather is expected for much of next week.
A few lightning strikes have occurred in North County, forecasters said Saturday. Rainfall amounts overall have been light — one-quarter inch or less — except on the coastal slopes, where one-half to as much as an inch had fallen.
Snow was reported around 4,500 feet Saturday morning, so the snow level may be near that, but is expected to rise closer to 5,000 Saturday afternoon, the NWS said. Some light snow accumulations have been reported above 5,000 feet.
“The storm will move away Sunday night with clearing skies, leading to a sunny midweek under seasonably cool conditions, though temperatures will gradually warm, but chilly nights are ahead,” forecasters said.
Late next week there is a high degree of forecast uncertainty as some models keep storm systems far enough north to leave Southern California dry, while others show additional rain as early as Thursday night through Friday.
Northwest winds of 15-25 knots with gusts to 30 knots are expected to continue in coastal waters through the weekend, along with combined seas of 8-12 feet and steep waves. The winds and swells will peak Saturday and Sunday before subsiding Monday.
A small craft advisory is in effect through early Monday morning for gusty winds and high combined seas, the NWS said. Periods of showers are likely Saturday night through Sunday night. No hazardous marine conditions are expected after Monday morning.
At the beaches, high surf is expected by the weather service through the weekend, with the highest surf Saturday afternoon through Sunday.
The highest surf is likely to occur in Imperial Beach and near the border, also producing a high risk of rip currents and dangerous swimming conditions.
Beachgoers were being warned to avoid contact with the water because of urban runoff pollution caused by rainfall.
“Swimmers, surfers and other water users are warned that rain brings urban runoff, which can cause bacteria levels to rise significantly in ocean and bay waters, especially near storm drains, creeks, rivers and lagoon outlets,” said Joseph Palmer of the San Diego County Department of Environmental Health. “Urban runoff may contain large amounts of bacteria from a variety of sources such as animal waste, soil and decomposing vegetation.”
Bacteria levels can remain elevated after a rainstorm, depending on the intensity of the storm, volume of runoff and ocean conditions, Palmer said.
“Water contact such as swimming, surfing and diving should be avoided during rain and for 72 hours following the rain event,” Palmer said.